As of July 1994 individuals diagnosed with AIDS who were both injection drug users (IDUs) and homosexually active men (MSMs) constituted 20% of all IDU AIDS cases in the United States; in many states that proportion is much greater, including the state of Washington where 61% of all IDU AIDS cases fall into this category. In Seattle that proportion is 70%. Little research has been conducted on this population to date (NIDA, 1994) and there are reports that MSM/IDUs are at significantly higher risk of HIV infection when compared with characteristics of persons meeting the 1993 AIDS case definition (Sorvillo, In Press, 1995). They may also represent a significant bridge population to both sexual and needle using partners of both genders. In particular MSM/IDUs who inject methamphetamine may represent an especially at risk population because of evidence that its use may predispose individuals to risk taking due to needle sharing as well as high risk sexual behavior due to disinhibition. Also ,methamphetamine use is increasing ([NIDA 1991, 1995, DAWN, 1991; NIDA-NHSD, 1992, Newmeyer, 1994; Wrede and Murphy, 1994, Arax and Gorman, 1995] and its use among homosexually active men may be contributing to a significant increase in HIV risk. We will use ethnographic methods including focus groups, observation and structured interviewing to describe ways in which methamphetamine use contributes to HIV risk through injection drug use and unprotected sex. In this exploratory study we will conduct interviews with homosexually active methamphetamine injectors in Seattle, Washington so as to :1) describe factors influencing the natural history of methamphetamine injection among MSMs; 2) characterize and describe common behaviors, and social patterns which provide the contexts for this drug use regarding unprotected sex and needle sharing; 3) describe preliminary typologies of social networks of MSM methamphetamine injectors and determine whether common injection patterns link gay and bisexual men with heterosexual men and women via sex or injection and 4) identify intervention points so as to inform the development of prevention and intervention strategies targeted to MSMs who use methamphetamines. This study will provide us with a better understanding of the dynamics of sexual and drug-related behaviors in this heretofore hidden and stigmatized population. To that end our findings will be able to better inform public health methamphetamine intervention efforts and will serve as a basis for a more comprehensive comparison with heterosexual injection drug users.